The present invention relates to eyeglass lenses, and, in particular, to vented eyeglass lenses.
Early dual-lens eyeglass systems generally comprised a right and left lens suspended by an eyeglass frame in the wearer's line of sight. Each of the right and left lenses was generally disposed on a plane which was perpendicular to the wearer's normal or "straight ahead" line of sight. Although the upper portion of the eyeglass frame generally contacts the forehead, a significant ventilation gap was normally present between the lower and lateral edges of the eyeglass lens and the wearer's cheek bone.
Dual lens eyeglasses have more recently been developed in which the eyeglasses exhibit a significant rake and wrap compared to the prior art.
Lens rake refers to the extent to which the lower edge of a lens curves in towards the wearer's face. One effect of enhancing rake in a dual lens system is to more closely conform the lens in the vertical plane to the head of the wearer.
Lens wrap refers to the extent to which the lateral edge of the lens curves rearwardly to conform more closely to the side of the wearer's head.
Increased lens rake and wrap have as a consequence a reduction in the gap between the lower edge of the lens and the face as well as a reduction in the gap between the lateral edge of the lens and the face.
Although increased rake and wrap in dual-lens eyeglasses produce a variety of benefits, one disadvantage is the entrapment of a relatively small volume of air between the lens and the wearer's face. When someone wears eyeglasses of this design during active sports, such as skiing, bicycling or the like, the lenses are susceptible to fogging on the inside surface due to an inadequate ability to circulate moisture-laden air.
Thus, there remains a need for a dual lens eyeglass system which permits a relatively high level of rake and wrap compared to the prior art, yet which minimizes the risk of fogging due to the entrapment of air between the lens and the face of the wearer.